How to Shingle a Valley

Roof valley installation has grown more complex with the flashing options, weaving techniques, and waterproofing requirements flying around. As someone who has shingled valleys on every roof type, I taught myself the working side of proper water management. Today, I will share it all with you.

Why Valleys Matter

Probably should have led with this topic, to be honest—valleys are where two roof planes meet, concentrating water runoff. Proper shingling ensures water drains without leaks.

Valley Methods

That’s what makes valley technique selection endearing to us roofers—each method has advantages:

Woven Valley

• Shingles from both sides interlace across valley
• Good water resistance when done correctly
• Works best with similar roof pitches

Closed Cut Valley

• One roof plane shingles extend across valley
• Other side shingles cut 2 inches from centerline
• Clean appearance with good water shedding

Open Valley

• Metal flashing exposed down valley center
• Shingles cut back from centerline on both sides
• Best for high-water-volume areas

Preparation

1. Install ice and water shield in valley
2. Ensure proper underlayment overlaps
3. For open valleys, install metal flashing

Installation Tips

• Never place nails within 6 inches of valley center
• Clip upper corner of shingles at valley angle
• Apply roofing cement under cut shingle edges
• Maintain consistent chalk line for straight cuts

Common Mistakes

• Nailing too close to valley center
• Inadequate underlayment or flashing
• Uneven cuts creating water channels
• Skipping roofing cement under cut edges